I assume it because star basketball players, either in college or the NBA, don’t, as a general rule, turn out to be good, faithful husbands and fathers when they impregnate their girlfriends. However, it’s possible that the young man’s losing his place on the team will lead to marriage, graduation from some college with a useful degree, and many years of happy family life. It certainly would be nice if that were the outcome.
I don’t know much about Mormons, but i don’t think the general stereotypes of NBA/college bball players are likely in a mormon school.